Gradation Air

Gradation Air, more commonly known as Projection (投影,touei?), is a Magecraft that materializes objects, in accordance to the caster’s imagination, through the use of prana. Gradation comes from the fact that the created object slowly fades away after being created, and Air is an allusion to the fact that said object is made out of “nothing”.

The concept behind this Magecraft is rather simple, to shape prana into the material composition and design of an object that is being imagined by the magus. The item is not everlasting, as it is recognized by the world as a phantasm that doesn't belong in the natural world, and it will be erased as an inconsistency. The better the image in the caster's imagination, the more stable and longer lasting the object will be, and it can be further improved by having technical knowledge of its construction, such as a blueprint, or having materials to overlay the desired shape upon.

Projection is considered to be an incomplete and mostly useless Magecraft by most modern magi for anything other than immediate activities, such as projecting a sacrificial item to be forsaken in a ritual. It is generally easier and more practical to create an object that will not fade away with appropriate techniques and raw materials. While Gradation Air is a more complex form of Reinforcement, it is ultimately inferior and less efficient. Comparatively speaking, if a magus uses Projection to recreate a sword while spending ten units of prana in the process, he will get a weapon with an overall strength of three or four. Meanwhile, if he uses that same prana to reinforce an existing blade, he will get a weapon with a power of twenty or thirty. It is also possible to apply Reinforcement to improve the capacities of the projected item.

Projection (Trace Version) (投影（トレース版）,?) is the personal variation of Gradation Air that Shirou Emiya and Archer use, referred as Tracing due the unique aria, "Trace On", that is used for its activation. Tracing greatly differs from normal Projection in the fact that not only does it reproduce the shape and substance of an object, but also its entire history as well. Objects created with tracing are slightly inferior to the originals due to the fact that only so much information can be gathered by sight alone, and Noble Phantasms are degraded by an entire rank. The only exception to this is Avalon, which Shirou can replicate perfectly due to his body preserving a complete record of it after having been fused with it for over a decade. Objects need to be seen directly in order to be traced, as even with a blueprint and materials, The Jeweled Sword of Zelretch was impossible to trace. Objects seen through shared memories, such as The Jeweled Sword of Zelretch and Caliburn seen through Justeaze Lizrich von Einzbern and Saber's eyes can be properly traced.

Shirou and Archer mentally divide the process of Tracing into seven steps, which include:

Judging the concept of creation

Hypothesizing the basic structure

Duplicating the composition material

Imitating the skill of its making

Sympathizing with the experience of its growth

Reproducing the accumulated years

Excelling every manufacturing process

Due to the extra effort, it is possible to produce incredibly stable ordinary items that can remain in the world for hours after their creation. Furthermore, whenever replicating mystical objects such as Noble Phantasms, it is possible to faithfully copy their special abilities and any skill that its owner performed are available for use. The reason this is possible is due to the nature of Unlimited Blade Works, which at a glance, records the history, composition, and design of what the user sees, and then provides the necessary materials needed to reproduce them. The actual reproduction happens within Unlimited Blade Works, and is then brought into the real world at need via Projection. If the image of the projection is interrupted in any way, the item will be physically weak and shatter upon physical impact. It is also possible to apply Reinforcement to objects recorded within Unlimited Blade Works, as demonstrated with Caladbolg II or Kanshou and Bakuya.